There are a variety of binding systems available on the market today. Among them are continuous spiral binders, wire loop binders, continuous wire loop binders and resilient plastic binders.
The resilient plastic binders presently in use include a specific construction identified by the term "plastic comb" which employs a mechanical spreading device for retracting the curved fingers away from a back connecting bar to permit insertion of the fingers through the pre-punched sheets and then releasing the spreading device to close the back connecting bar around the fingers and capture the sheets on the fingers. Except for conventional split ring loose leaf binders, most of the present systems are constructed to permit only assembly of the paper sheets on the binding apparatus with the aid of a separate mechanical holding and/or spreading mechanism. This does not permit the sheets to be readily removed or additional sheets to be added to the bound booklet, without using such a mechanism.
The inventor has previously disclosed (Ser. No. 07/290,563, BOOKLET BINDER SYSTEM) a continuous wire loop binding unit which consists of the conventional continuous wire or plastic loop unit and an elongated closure unit removably inserted between the two rows of loops. The closure unit of applicant's prior unit includes a pair of spaced apart grooves respectively receiving the two rows of loops to interlock therewith. In one form of the prior unit a locking strip overlies a pair of hinged closure elements to hold the elements interlocked in closure position between the rows of loops.
Also disclosed in the prior application was another form of the invention which includes a unitary rigid closure unit with the wire loop fitting into the grooves of the closure unit. The rigid closure unit slides over the ends of the tines to form the binding unit. This unit has no effective means for maintaining it in closure position.